The dip is considered modest after months of double- digit declines. Overall trade dropped 17.6 percent at the port during November when compared with the same month in 2010. Imports dipped 15.6 percent, with exports down 22 percent.

In all, nearly 460,000 containers moved through Long Beach during November.

The port attributes the "relatively flat" traffic to the departure of one of its major tenants.

California United Terminals, which vacated a large site on Pier E and moved to a newly renovated terminal in the Port of Los Angeles last summer, accounted for about one-tenth of container traffic in Long Beach.

"That's definitely a major loss," said Ferdinando Guerra, an associate economist for the Los Angeles Economic Development Corp.

Without California United, the six terminals remaining in Long Beach actually posted an 8.1 percent increase in 2011. Their imports jumped 10.1 percent and exports by 7.8 percent. In December, overall container traffic was up by 1.7 percent from 2010 at the remaining terminals. But while imports were up 1.8 percent in December, exports fell 4.5 percent.

Guerra said the drop in exports could also be attributed in part to the global slowdown in China and other parts of the Pacific Rim. The tsunami in Japan also affected the level of autos, auto parts and electronic goods flowing into Long Beach.

Also an impact is the rising cost of oil and the credit and trade finance issues in Europe.